The present invention pertains to a covering system for truck containers.
The construction and sanitation industries utilize trucks to haul open containers that transport loose materials. The open top containers are frequently provided with a fabric or a tarpaulin which covers the load being transported in order to either protect the load or prevent parts of the load from being blown out of the container.
Open top containers are ordinarily formed as separable units that can be secured to the frame of a truck for transport and then removed from the truck for use at a desired site. These containers are typically used with so-called roll-off trucks. Open top containers can be used, for example, to receive and contain trash at a construction site. The containers are generally only loaded onto a truck for transport. The containers have a generally rectangular box shape, but vary in loading capacity from 10 cubic yards to 50 cubic yards. The containers vary widely in both length and height, with the sidewalls generally ranging from 4-8 feet in height and 10xe2x80x2-35xe2x80x2 in length. Most containers in use today are 4xe2x80x2, 6xe2x80x2 or 8xe2x80x2 high and 17-24 feet long. Still some containers in use have a rear wall higher than the rest of the container.
U.S. Pat. No. 5,031,955 issued to Searfoss illustrates a truck covering system for a fixed dump body. Arms located laterally of the dump body are connected to a tarpaulin to selectively cover the open top of the dump body. This covering system is not designed for trucks that carry interchangeable open top containers of different lengths and heights. Further, these systems use arms with a fixed swinging stroke or arms with telescoping segments. A system with a fixed stroke cannot accommodate different sized containers and may experience difficulty in covering loads that project above the top edges of the container, especially at the front or rear of the container. While telescoping arms provide some adjustment of the swinging stroke, they require manual adjustment, are susceptible to being bent and rendered non-adjustable even if bent only a little, and require a higher level of maintenance to keep the telescoping segments cleaned and operable.
Past covering systems for roll-off trucks have generally relied upon a tarpaulin which extends over the top opening of the container and retracts to a stowed position. While the past systems help to cover the load for transportation, the arrangements that move the tarpaulin have suffered from a variety of drawbacks. In one case, U.S. Pat. No. 5,340,187 issued to Haddad describes a truck covering system with telescoping arms. Although the telescopic arms accommodate variations in the lengths of the containers, they, as noted above, require high maintenance and are susceptible to being damaged and rendered inoperable.
In other examples, U.S. Pat. No. 5,829,818 to O""Daniel and U.S. Pat. No. Re 36,135 to O""Brian describe truck container covering systems wherein the arms are pivotally secured at a midsection of the truck bed so as to swing about a transverse axis and cover or uncover the container. However, during loading and unloading of the container on the truck, the container can slide laterally and strike against and damage the arms and/or pivot connection. The fixed connection of the arms to the bed provides no flexibility and is thus susceptible to being broken by such contact. Moreover, heavy materials dumped into open containers sometimes cause the sidewalls to bow outward. This fixed pivot arrangement of the arms at a midsection of the truck bed may not accommodate the increased width of the container as it is loaded onto the truck.
During transportation of the containers, the arms are subjected to dynamic loads from rough road surfaces. As a result, when the tarp is stretched across the rear end of the container, the arms may bounce upward and release some of the load inside the container. None the above covering systems adequately address this problem.
The present invention pertains to a container covering system for open top containers provided with enhanced control and maneuverability for covering containers of different sizes without high risk of damage and/or high maintenance requirement of past systems.
In accordance with one aspect of the present invention, a tarp is extended and retracted by an articulated arm assembly provided along each side of the truck bed. Each arm assembly includes a first arm that is secured at a front location of the truck bed, and a second arm that is pivotally secured to the rear end of the front arm. In this way, the fixed connection of the arms to the truck bed is located at a forward location where it is less likely to be struck by a wayward container being loaded or unloaded from the bed. The rearward extension of the arms possesses a certain amount of flexibility to accommodate some contact between the arms and the container without damaging the covering system.
In accordance with another aspect of the invention, the first arms are pivotally secured to the truck for enhanced adjustability in covering various size containers as well as retracting. The pivotal movement of the first arms is controlled by at least one actuator that is able to swing the arms upward or downward as needed in covering or uncovering the container. Moreover, in one preferred construction, the arms are secured to a vertically adjustable tower to further enhance its capacity to cover containers of varying heights and any projecting or heaped loads in the containers.
In one embodiment of the invention, the second arms are operatively coupled to the tarp and are constantly biased to swing toward the rear end of the container to naturally extend the tarp over the container. The arms are, however, held in place until the tarp device is actuated to play out or retract the tarp. More specifically, the tarp is extended by rotating the roller bar of the tarp device holding the stowed tarp. In this way, the bias of the second arms in cooperation with the operation of the tarp device maintains the tarp under tension and extends the tarp over the container in a smooth and uniform manner. Moreover, the use of the springs eliminates the need for the arm assemblies to support hydraulic cylinders and thus reduces the weight and the stress on the arms.
In another aspect of the invention, the arms are preferably composed of a material having a high strength to weight ratio. In one embodiment, the material can be a fiber reinforced composite. In this way, the stress and fatigue on the components of the system are reduced so as to extend the operational life of the system.
In a further aspect of the invention, the rear arms have a flexible portion disposed along a predefined length of the arms so as to provide a further adjustment for moving the leading end of the tarp to the extended position and a shock absorption means to reduce stress on the arms.
The above and other aspects, features and advantages of the present invention will be readily apparent and fully understood from the following detailed description of preferred embodiments.